PIGA mutations and glycosylphosphatidylinositol anchor dysregulation in polyposis-associated duodenal tumorigenesis

The pathogenesis of duodenal tumours in the inherited tumour syndromes Familial Adenomatous Polyposis (FAP) and MUTYH-associated Polyposis (MAP) is poorly understood. This study aimed to identify genes that are significantly mutated in these tumours and to explore the effects of these mutations. Whole exome and whole transcriptome sequencing identified recurrent somatic coding variants of PIGA in 19/70 (27%) FAP and MAP duodenal adenomas, and further confirmed the established driver roles for APC and KRAS. PIGA catalyses the first step in glycosylphosphatidylinositol (GPI) anchor biosynthesis. Flow cytometry of PIGA-mutant adenoma-derived and CRISPR-edited duodenal organoids confirmed loss of GPI anchors in duodenal epithelial cells and transcriptional profiling of duodenal adenomas revealed transcriptional signatures associated with loss of PIGA. Implications: PIGA somatic mutation in duodenal tumours from patients with FAP and MAP and loss of membrane GPI-anchors may present new opportunities for understanding and intervention in duodenal tumorigenesis.

Burden and Profile of Somatic Mutation in Duodenal Adenomas from Patients with Familial Adenomatous- and MUTYH-associated Polyposis

Purpose: Duodenal polyposis and cancer are important causes of morbidity and mortality in familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP). This study aimed to comprehensively characterize somatic genetic changes in FAP and MAP duodenal adenomas to better understand duodenal tumorigenesis in these disorders.Experimental Design: Sixty-nine adenomas were biopsied during endoscopy in 16 FAP and 10 MAP patients with duodenal polyposis. Ten FAP and 10 MAP adenomas and matched blood DNA samples were exome sequenced, 42 further adenomas underwent targeted sequencing, and 47 were studied by array comparative genomic hybridization. Findings in FAP and MAP duodenal adenomas were compared with each other and to the reported mutational landscape in FAP and MAP colorectal adenomas.Results: MAP duodenal adenomas had significantly more protein-changing somatic mutations (P = 0.018), truncating mutations (P = 0.006), and copy number variants (P = 0.005) than FAP duodenal adenomas, even though MAP patients had lower Spigelman stage duodenal polyposis. Fifteen genes were significantly recurrently mutated. Targeted sequencing of APC, KRAS, PTCHD2, and PLCL1 identified further mutations in each of these genes in additional duodenal adenomas. In contrast to MAP and FAP colorectal adenomas, neither exome nor targeted sequencing identified WTX mutations (P = 0.0017).Conclusions: The mutational landscapes in FAP and MAP duodenal adenomas overlapped with, but had significant differences to those reported in colorectal adenomas. The significantly higher burden of somatic mutations in MAP than FAP duodenal adenomas despite lower Spigelman stage disease could increase cancer risk in the context of apparently less severe benign disease. Clin Cancer Res; 23(21); 6721-32. ©2017 AACR.

The Welsh Institute for Minimal Access Therapy colonoscopy suitcase has construct and concurrent validity for colonoscopic polypectomy skills training: a prospective, cross-sectional study

BACKGROUND

The Welsh Institute for Minimal Access Therapy (WIMAT) colonoscopy suitcase is an ex vivo porcine simulator for polypectomy training.

OBJECTIVE

To establish whether this model has construct and concurrent validity.

DESIGN

Prospective, cross-sectional study.

SETTING

Endoscopic training center.

PARTICIPANTS

Twenty novice (N), 20 intermediate (I), 20 advanced (Ad), and 20 expert (E) colonoscopists.

INTERVENTION

A simulated polypectomy task aimed at removing 2 polyps; A (simple), B (complex).

MAIN OUTCOME MEASUREMENTS

Two accredited colonoscopists, blinded to group allocation, scored performances according to Direct Observation of Polypectomy Skills (DOPyS) assessment parameters. Group performances were compared. Real-life DOPyS scores were correlated to simulator DOPyS results.

RESULTS

Median overall DOPyS scores for novices were 1.00 (1.00-1.87) for A and 0.50 (0.00-1.00) for B (A vs B; P < .01). Intermediates scored 2.50 (2.00-2.88) for A and 2.00 (1.13-2.50) for B (A vs B; P = .03). The advanced group scored 3.00 (2.50-3.50) for A and 2.50 (2.00-3.00) for B (A vs B; P = .01). Experts scored 3.00 (3.00-3.88) for A and 3.00 (2.50-3.50) for B (A vs B; P = .47). Intergroup comparisons for A were, N vs I; P < .01, N vs Ad; P < .01, N vs E; P < .01, I vs Ad; P < .01, I vs E; P < .01, and Ad vs E; P = .46. Intergroup comparisons for B were, N vs I; P < .01, N vs Ad; P < .01, N vs E; P < .01, I vs Ad; P = .03, I vs E; P <.01, and Ad vs E; P = .06. There was no difference between real-life DOPyS scores and simulator scores (0.07).

LIMITATIONS

The model does not have inbuilt assessment parameters.

CONCLUSION

This simulator demonstrates construct and concurrent validity for colon polypectomy training.

Gastrointestinal polyposis syndromes for the general gastroenterologist

The occurrence of colonic polyps is a common phenomenon; however, where there are numerous adenomas or other polyps, and/or the patient is at a relatively young age, an inheritable form of gastrointestinal polyposis should be considered. Patients can present via different referral routes, for example, at colonoscopy where multiple polyps are detected, following a personal diagnosis of colorectal cancer, or by family screening. This article outlines the important considerations in the diagnosis of a polyposis syndrome and key diagnostic features to consider. It will also describe the underlying genetic factors associated with the common polyposis syndromes, including classical familial adenomatous polyposis (FAP), attenuated FAP, MUTYH-associated adenomatous polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome and serrated polyposis, and the subsequent management of each condition.

The molecular genetics of colorectal cancer

Colorectal cancer is a common but heterogeneous disease, which arises through the accumulation of genetic mutations. Knowledge of the molecular basis of colorectal cancer has advanced at a rapid pace in recent years, reflecting progress made in the field of genomic medicine. Targeted therapies have come into mainstream use, and the exciting prospect of treatment regimens tailored to the mutation profile of individual tumours is beginning to emerge. In order to understand the development and application of the next generation of colorectal cancer treatments, it is important that gastroenterologists have a working knowledge of the pathological mechanisms that drive the disease. This review examines our current understanding of the molecular genetics of colorectal carcinogenesis.

Can endoscopists accurately self-assess performance during simulated colonoscopic polypectomy? A prospective, cross-sectional study

BACKGROUND

The aim of this study was to establish if endoscopists can reliably self-assess their ability to perform simulated colonic polypectomy.

METHODS

Novices, intermediates, advanced, and experts performed a video-recorded polypectomy task using the Welsh Institute for Minimal Access Therapy (WIMAT) colonoscopy suitcase simulator. This involved removal of a simple polyp (A) and a complex polyp (B). Participants self-assessed themselves using a Direct Observation of Polypectomy Skills (DOPyS) assessment form. Two blinded, independent, Joint Advisory Group on Gastrointestinal Endoscopy (JAG) accredited assessors graded each performance using the same DOPyS scoring. The Spearman coefficient was used to determine the correlation between self and assessors' scores.

RESULTS

Eighty participants completed the task. There was a weak correlation between assessors' scores and self-assessment scores for all groups (novices: ρ = -.44, P = .85; intermediates: ρ = -.16, P = .51; advanced: ρ = .16, P = .50; and experts: ρ = .07, P = .76). There was a strong correlation between scores from assessor 1 and 2 for polyp A (ρ = .80, P ≤ .01) and polyp B (ρ = .80, P ≤ .01).

CONCLUSIONS

The correlation between self-assessment and assessors' scores is weak. Novices and intermediates underestimate performance, whereas advanced and experts overestimate performance. Regular feedback may improve accuracy.

Helping the general physician to improve outcomes after PEG insertion: how we changed our practice

During their careers, most general physicians are involved in the decision-making process for patients that potentially require percutaneous endoscopic gastrostomy (PEG) insertion. However, poor patient selection and less than favourable outcomes are frequently observed in this group. With the aim of identifying and addressing the underlying issues, the PEG service at University Hospital Llandough was radically changed over an eight-year period. The development of a nurse-led pre-assessment service and design of a specific referral form was successful in reducing the number of PEG referrals and consequently the 30-day mortality rate. Furthermore, the educational and training needs of general physicians of all grades regarding the issues surrounding PEG placement were identified and addressed at formal teaching sessions. A combination of these factors has positively impacted on our service, with more appropriate patient selection and a reduced 30-day mortality rate.

Asymptomatic severe carotid stenosis

The management of asymptomatic carotid stenosis remains controversial. From December 1983 to December 1987, 188 symptom-free patients were found to have severe (greater than 75%) stenosis by duplex imaging (performed as screening examination). Patients with non-hemispheric symptoms or contralateral symptomatic lesions (within 7 years) were excluded from the study. Follow-up data were available for 141 patients (range 3 to 36 months; mean 21 months). Sixty-two patients received nonoperative therapy. The remaining 79 patients underwent 100 carotid endarterectomies (CAE) (21 staged bilateral repairs and 58 unilateral repairs). There were no statistically significant differences in sex, age, or risk factors (i.e., hypertension, diabetes, or smoking) or in the incidence of bilateral disease. Significant differences were found in the incidence of ischemic attacks (0 vs 21%; p less than 0.001) and stroke (2.5% vs 18%; p less than 0.01) in the operative vs nonoperative group. None of the 11 strokes in the nonoperative group were preceded by neurologic events. The operative group had an overall stroke rate of 2.5% (2/79), a perioperative mortality rate of 1.3% (1/79), and a restenosis (greater than 50%) rate of 3.8% (3/79). Thus favorable results can be achieved with prophylactic CAE. These data support the use of prophylactic CAE in any patient with greater than 75% stenosis identified by duplex image, regardless of sex, age, risk factors, or bilateral disease.

The use of deep duplex scanning to predict hemodynamically significant aortoiliac stenoses

Hemodynamic assessment of aortoiliac occlusive disease is necessary for successful arterial reconstruction of the aorta and legs. Various methods have been proposed and "pull-through" intra-arterial pressures are the "gold standard." Deep Doppler duplex imaging was supplemented with real-time spectral analysis and velocity measurements in 29 cases. Twenty-three of these patients needed arteriography. One hundred sixty-six (166) arterial segments extending from the proximal aorta to the common femoral arteries were independently graded on duplex scans and arteriograms. For severe occlusive disease, duplex scanning is highly accurate (sensitivity 82%, specificity 93%). Velocity measurements were useful in determining the hemodynamic significance of stenoses. Peak systolic velocities in stenoses were measured with a duplex scanner. The pressure gradient calculated with the modified Bernoulli equation (delta P = 4Vmax2) correlated well with the gradients measured during arteriography (r = 0.9, n = 11). These noninvasive velocity measurements and Bernoulli calculations alert arteriographers to obtain special views of suspected areas and suggest the need for "pull-through" pressures and possible balloon angioplasty. In addition, these noninvasive measurements are useful to follow up patients who have mild to moderate aortoiliac disease and after angioplasty.

Distal arterial reconstruction: patency and limb salvage in diabetics

Controversy regarding efficacy and durability of distal bypass grafting of the diabetic patient exists. A 22-year-long series of 259 vascular procedures with 100% follow-up (57% in diabetic individuals) is examined to compare these results with those of non-diabetic patients. Extensive review of predisposing factors, operative indications, preoperative medical evaluation, as well as techniques and peculiarities of angiography is rendered. Peripheral arterial case mix between the two groups is examined. The high utilization rate of solely venous conduits (94%) in diabetics compared with 76% in nondiabetics, along with anastomosis site selection, provides the most reasonable explanation for the successful outcome in both groups. Modifications in revascularization techniques contributing to successful outcome are presented. In the diabetic patients, both the cumulative graft patency rate (63%) and the limb salvage rate (77%) at 6 years were superior to those of the non-diabetics (52% and 65%, respectively). Diabetes mellitus does not predispose the person requiring revascularization for limb salvage to a lesser likelihood of success.

Duplex B-mode imaging for the diagnosis of deep venous thrombosis

Real-time B-mode venous imaging has numerous advantages for the diagnosis of acute deep venous thrombosis (DVT). During the 11 months ending Feb 1, 1986, we examined 431 patients for possible acute DVT using a 5-MHz hand-held continuous wave Doppler stethoscope and a duplex real-time B-mode imager. Clots were seen in 86 patients in multiple views and cross sections. Normal veins completely collapsed with probe pressure on the skin. Blood flow was seen and heard, and abnormal flow was detected. There were no false-negatives (100% sensitivity). Early in the study, two false-positives occurred (78% specificity), but these errors will not recur. These tests are accurate, noninvasive, and inexpensive. They differentiate acute from chronic thrombosis and are repeatable. Duplex imaging may become the "gold standard" for the diagnosis of DVT.

Serratia liquefaciens mastitis in a dairy herd

Serratia liquefaciens mastitis was detected and investigated in a 41-cow Holstein herd. Twenty cows were treated for mastitis over a 3-month period. Serratia liquefaciens was isolated from milk samples obtained from 8 of 12 cows tested during the epizootic. Results of an epidemiologic investigation suggested that extensive frostbite of the teats decreased the udder defense. Poor milking technique and hygiene were responsible for increased exposure of the damaged teats to potential udder pathogens. Treatment of each cow resulted in initial clinical improvement, but exacerbations occurred in 75% of the cows with documented S liquefaciens infections.

Comparison of initial limb salvage in 98 consecutive patients with either reversed autogenous or in situ vein bypass graft procedures

A retrospective review of 98 consecutive patients undergoing femoropopliteal or distal bypass procedures was conducted to determine whether in situ bypass grafting offers statistically significant initial limb salvage over reversed autogenous techniques. Over a 40 month period, 98 consecutive patients received either in situ or reversed autogenous vein grafts to effect limb salvage. The groups were similar in incidences of diabetes and previous myocardial infarctions, as well as in site of distal anastomosis (beneath the tibial peroneal trunk in more than 80 percent). The in situ vein graft group had an overall limb salvage rate of 92 percent with an 88 percent cumulative patency rate at 4 to 18 month follow-up, whereas the reversed autogenous vein graft group had a limb salvage rate of 86 percent with a 79 percent cumulative patency rate at up to 18 months. Results after 30 days showed 47 patients had improvement and 3 patients (6 percent) had died in the in situ vein graft group. In the reversed autogenous vein graft group, 44 patients improved, 4 did not improve and required amputations, and 2 (1 percent) died. Our study supports the use of in situ vein bypass grafting for limb salvage.

Surgical implications of fibrinolytic therapy

Intraarterial fibrinolytic therapy was used in 37 cases (34 patients) of severe peripheral ischemia. Nineteen patients (56 percent) required surgical intervention (5 amputations and 14 successful reconstructive procedures). Twenty-four patients (71 percent) were significantly improved (average ankle-to-arm index 0.84), whereas only 5 patients (15 percent) lost their limbs. Five patients were angiographically unchanged with no or slight improvement in the ankle-to-arm index (0.22 to 0.32) and were discharged on anticoagulant therapy. One death and two cerebrovascular accidents occurred. The usefulness of intraarterial fibrinolytic therapy needs to be evaluated within the total realm of vascular surgery. It offers options for therapy where previously none existed. Some situations might be treated equally well with either intraarterial fibrinolytic therapy or surgery. Finally, surgery might be required to maintain initial successful results with intraarterial fibrinolytic therapy or to rescue intraarterial fibrinolytic therapy failures in striving to achieve superior results in limb salvage.

Distal tibial vein grafts for limb salvage

Bypasses below the tibial peroneal trunk, which are not commonly performed, are an effective method of limb salvage. We have done long-term follow-up of all 148 consecutive grafts done during the past 19 years. By careful patient selection, detailed arteriograms, utilization of veins from all extremities, meticulous operating technique, and noninvasive follow-up, we have achieved a limb salvage rate of 75% and a cumulative five-year patency rate of 62%. Diabetics made up 53% of the series and did not affect the results. Seventy-one percent of all failures occurred in the first six months. Considering the charges for hospitalization, amputation, prostheses, and rehabilitation, distal tibial bypass procedures are cost-effective.